This invention relates to a knock suppression apparatus for an internal combustion engine, such as a multi-cylinder automotive engine.
Engine knocking is a form of abnormal engine vibration which occurs when the ignition timing of an internal combustion engine is unsuitable for the current operating conditions of the engine. The occurrence of knocking in an engine not only decreases the ride comfort and worsens the fuel economy of the vehicle in which the engine is installed, but it can also damage the engine. Therefore, automotive engines are typically equipped with knock suppression apparatuses which detect the occurrence of knocking and then adjust the ignition timing in the lag angle direction until the knocking stops.
With a conventional knock suppression device, when knocking is detected during the power stroke of cylinder number n in the firing order of an engine, the processing time of the knock suppression apparatus is such that there is insufficient time to adjust the ignition timing for the next cylinder (cylinder n+1) in the firing order to compensate for knocking, especially at high engine speeds, and the earliest cylinder for which the ignition timing can be adjusted is cylinder number (n+2) in the firing order. In other words, there is always a lag of one cylinder after knocking is sensed before the ignition timing can be adjusted to compensate for knocking. Accordingly, there is a need for a knock suppression device with a faster response time.